The teaching of music theory has often been accompanied by instruction on a keyboard instrument, such as a piano. Keyboard instruction provides the student with a means for visualizing the arrangement and relationship of notes and scales which would otherwise not be provided by the isolated study of music on other instruments.
Visual teaching aids have been developed to replace keyboard instruction. However, prior devices have been an inadequate substitute in providing a complete means for visualizing the order and relationship of every key and every triad or chord contained therein, as perceived from every mode.